Microenvironmental niches dictate divergent fibroblast fates in reversible versus progressive lung fibrosis.

BACKGROUND

Fibroblast behaviour is a key determinant of outcomes in interstitial lung diseases (ILDs), yet mechanisms governing the switch between reversible repair and progressive fibrosis remain unclear. How disease-specific cellular niches shape fibroblast fate across ILD phenotypes has not been compared in situ.

METHODS

We profiled peripheral lung tissues from controls, organising pneumonia (OP), connective tissue disease-associated ILD (CTD-ILD), and idiopathic pulmonary fibrosis (IPF) using High-Definition Visium spatial transcriptomics. A matched single-cell RNA-seq atlas was integrated via robust cell-type deconvolution to map cellular neighbourhoods. Differential expression and pathway activity were validated by immunofluorescence. Predicted ligand-receptor mechanisms and fibroblast responses were tested in vitro under glucocorticoid (GC), TGF-β1, and B-cell/MIF perturbations with receptor blockade.

FINDINGS: Disease-specific niches were tightly coupled to fibroblast states. OP exhibited B-cell-AT2-myofibroblast-enriched niches with high GC responsiveness and apoptosis. IPF was dominated by bronchiolised epithelium, alongside myofibroblasts exhibiting glucocorticoid resistance and strong matrix programmes. CTD-ILD exhibited macrophage-rich niches with multinucleated giant cells. In vitro, GC induced NR3C1-mediated apoptosis in fibroblasts, whereas TGF-β1 drove a senescent, GC-resistant phenotype. IgD + B-cell-derived MIF enhanced fibroblast migration via CD74, an effect blunted by TGF-β1. Thus, niche composition dictates fibroblast fate, distinguishing GC-sensitive resolution from apoptosis-resistant fibrosis.

INTERPRETATION: A GC-sensitive, apoptosis-prone myofibroblast niche in OP may underpin reversibility, whereas CTD-ILD and IPF follow distinct trajectories driven by immune dysregulation and epithelial-stromal maladaptation. These spatial microenvironmental signatures nominate therapeutic targets and may inform precision therapy for fibrotic lung disease.

FUNDING: The National Natural Science Foundation of China (82172109 to L.X., 82570001 to H.C.), the Ministry of Science and Technology of the People's Republic of China (2023YFC3502605, 2024YFA1108906) (H.C.), the Natural Science Foundation of Tianjin, China (25JCZDJC01260) (H.C.); the Key Laboratory of Medical Rescue Key Technology and Equipment, Ministry of Emergency Management (Open Fund Project No. YJBKFKT202410).